Stabilized 1-phenyl-3-pyrazolidone photographic developer system



A. A. BALDONI ETIAL 3,369,898 STABILIZED l-PHENYL-5-PYRAZOLIDONE PHOTOGRAPHIC DEVELOPER SYSTEM Filed Feb. 5, 1967 Feb. 20, 1968 80 lOb IL J 20 INVENTORS ANDREW A. BALDON/ BY SHUJ/ K/MURA PE/VDLE TON, NEUMAN SE/BOLD 8 W/LLMMS ATTORNEYS VOLUME ACETIC ACID I VOLUME WATER O z w m a United States Patent 7 Claims. (11. 96-66.1)

ABSTRACT OF THE DISCLOSURE A process for developing photographic silver halide emulsions which comprises providing a stabilized developing system comprising:

(a) providing a component package comprising a solution of a 1-phenyl-3-pyrazolidone developing agent, said solution consisting essentially of an aqueous acetic acid solution of a 1-phenyl-3-pyrazolidone developing agent, said solution being characterized in being stable during storage for more than one year at ambient temperatures,

(b) providing another component package solution comprising a developer composition containing alkaline components and developer components free from a 1- phenyl-S-pyrazolidone developing agent,

(c) storing said component package solutions in separate unmixed condition,

(d) admixing said developing agent component solution to form a developing solution for silver halide emulsion at the time of use,

(e) and developing a silver halide emulsion in said admixture.

This application is a continuation-in-part of application Ser. No. 306,905, filed Sept. 5, 1963.

This invention relates to new and improved photographic developer solutions and to a new method of making stable photographic developing baths having full speed, contrast and capacity.

The reducing agent employed in the developing solutions of the present invention is a derivative of a well known class of reducing agents, the 3-pyrazolidones, particularly 1-phenyl-3-pyrazolidone, represented by the following structural formula:

I CeH It is Well known in the photographic art to use alkaline aqueous developer concentrates containing materials such as sodium sulfite, potassium bromide, sodium carbonate, sodium hydroxide, hydroquinone, and benzotriazole for subsequent dilution with water prior to use. 1-phenyl-3- pyrazolidone has also been used in conjunction with hydroquinone in alkaline aqueous developer concentrates of the type described above for the purpose of achieving enhanced developing activity.

It was heretofore customary to prepare developing concentrates by incorporating the 1-phenyl-3-pyrazolidone developer in an alkaline developing bath of the type described.

A serious disadvantage developed in the use of 1- phenyl-3-pyrazolidone in alkaline aqueous developer concentrates due to the decomposition of 1-phenyl-3-pyrazolidone and loss of photographic activity upon long stand- "ice ing or storage. It was observed that l-phenyl-B-pyrazolidone in such alkaline aqueous medium was subject to deterioration and instability upon storage, breaking down to form products which have poor developing action, re sulting in loss of contrast, speed and capacity. This phenomenon is disclosed by G. C. Alletag, Photographic Science and Engineering, Volume 2, pages 213-218 (1958).

This storage instability, apparently due to hydrolysis of 1-phenyl-3-pyrazolidone, rendered an otherwise advantageous developing agent undesirable for general use under commercial conditions where developers are normally stored for long periods of time before use.

One method of circumventing the hydrolysis disadvantage inherent in the use of a 3-pyrazolidone compound was provided by the process of Alletag US. Patent No. 3,038,801, June 12, 1962. There it was asserted that storage instability is due to the hydrolysis of the 3-pyrazolidone compound which in turn is caused by the presence of water. The decomposition problem was there alleviated by separate packaging of a concentrate of a 3-pyrazolidone reducing agent in a non-aqueous organic solvent, apart from a conventional alkaline aqueous developing bath, requiring a mixture of the two solutions prior to use to form the final developing solution.

However, the use of non-aqueous organic solvents for the dissolution of a 3-pyrazolidone reducing agent is disadvantageous in certain respects. It practically precludes the dissolution in the 3-pyrazolidone solution of some of the inorganic salts normally present in the conventional developing bath, such as sodium or potassium bromide, thereby limiting the versatility of such a solution from a formulating standpoint. In addition, it increases the cost of the developer solution, making it less competitive with other aqueous developer solutions.

Accordingly, it is an object of this invention to provide aqueous solution of a 3-pyrazolidone reducing agent in which the 3-pyrazolidone reducing agent is stable, even after prolonged storage.

It is another object of this invention to provide aqueous solutions of a 3-pyrazolidone reducing agent in which the 3-pyrazolidone reducing agent is stable and where the resultant solution is misciblewith a conventional developing solution.

A further object is the provision of aqueous solutions of a 3-pyrazolidone reducing agent which solutions are stable during storage and miscible with conventional photographic developing baths to provide photographic developing baths having full speed, contrast and capacity, even after prolonged storage of the reducing agent solution.

The fulfillment of these and other objects of this invention may be seen from the following specification and appended claims.

Broadly the present invention comprises a stabilized two-component package developer system for admixture at the time of use, one component package comprising a solution of 1-phenyl-3-pyrazolidone consisting essentially of from 15 to by volume of aqueous acetic acid and at least about 2 grams of l-phenyl-Z-pyrazolidone per ml. of acetic acid solution, and a second component package comprising a developer composition containing alkaline components and developer components other 7 than 1-phenyl-3-pyrazolidone.

portions of acetic acid and Water in the solution, and the ordinate represents the amount of 1-phenyl-3-pyrazolidone soluble in a solution of given proportions in grams per 100 milliliters of the aqueous acetic acid solution. The curve A, B, C represents the maximum l-phenyl-3-pyr- :azolidone that is soluble in a water-acetic acid solution of given proportions. Thus in one broad form the present invention comprises compositions of proprtions falling in the area of the figure interconnecting the points A, B, C and D in the accompanying drawing. In this broad range the proportions are from about 16 to 95 volume percent acetic acid and l-phenyl-3-pyrazolidone in a proportion of from about 2 to about 36 grams per 100 ml. of solution. The area defined by interconnecting points E, B, C and D represents the various proportions of the most preferred compositions of this invention and ranges from about 70 to 95 volume percent acetic acid, and from 2 to 36 grams of 1-phenyl-3-pyrazolidone per 100 ml. of the aqueous acetic acid solution.

In accordance with the objects of the present invention, aqueous acetic acid solutions of 1-phenyl-3-pyrazolidone are provided which are stable for more than one year at ambient temperatures. These aqueous reducing agent solutions of 1-phenyl-3-pyrazolidone are packed separate and apart from the developing solutions into which they are to be incorporated. The final developing solution is prepared by admixing the aqueous reducing agent solution with the developing solution prior to use.

Acetic acid is a particularly useful solvent medium because of its complete miscibility with developing solutions, its non-reactivity with sensitized photographic film, its capacity for dissolving sufficient quantities of l-phenyl- 3-pyrazolidone, its relatively low cost and general acceptance by the photographic trade.

For a more complete understanding of the present invention, reference is now made to the following specific examples illustrating the method and compositions employed in the provision of stable aqueous 1-phenyl-3- pyrazolidone solutions and the procedure for evaluating storage stability of aqueous reducing agent solutions.

EXAMPLE I In this and the following examples the developing solution is divided into two separate solutions consisting of Part A, which is a conventional developer concentrate, and Part B, which is a reducing agent solution of 1- phenyl-3-pyrazolidone. Each part is packed separately and mixed with the other prior to use. Additional water is added to the mixture to provide a final use developing bath.

STORAGE CONDITIONS For the purpose of evaluating the storage stability of the aqueous solution of 1-phenyl-3-pyrazolidone, Part B was stored in a sealed amber bottle and maintained at 50 C. for a period of four weeks. Storage at 50 C. for four Weeks is equivalent to about 14 months at C. It is also considered the most useful accelerated test condition since it results in a convenient degradation interval which extends over several weeks, making periodic testing prac- .tical and minimizing test errors. The 50 C. temperature also provides more meaningful information since it represents the approximate maximum temperature encountered under field conditions of transit and storage in the United States. (See G. C. Alletag in Photographic Science and Engineering, vol. 2, pp. 214, 215 and 217.) At the end of four weeks storage, Part B was mixed with Part A, freshly prepared, in the following proportions: Twenty-five milliliters of Part B were mixed with one liter of Part A, and the resultant solution was diluted to four liters to prepare the final use developing bath. The developing efficiency of this final use developing bath, when compared with a final use developing bath made with fresh reducing agent solution (Part B), is a measure of the stability of the 1-phenyl-3-pyrazolidone solution. The developing characteristics of the aged solution and the control are set forth in Table 1.

EXAMPLE II Part A (Same as in Example I.)

Part B Ingredient: Quantity Glacial acetic acid milliliters 90 Water doi 10 l-phenyl-3-pyrazolidone grams 2O STORAGE C ONDITIONS Part B was stored and subsequently mixed with Part A as described in Example I. The resultant solution was diluted in the same manner as in Example I. The developing characteristics of the aged solution are set forth in Table 1.

EXAMPLE III Part A (Same as in Example I.)

Part B Ingredient: Quantity Glacial acetic acid milliliters Water do 20 1-phenyl-3-pyrazolidone grams 20 STORAGE C ONDITI ONS Part B was stored and subsequently mixed with Part A as described in Example I. The resultant solution was diluted in the same manner as in Example I. The developing characteristics of the aged solution are set forth in Table 2.

EXAMPLE IV Part A (Same as in Example I.)

Part B Ingredient Quantity Glacial acetic acid milliliters 70 Water do 30 1-phenyl-3-pyrazolidone grams 20 STORAGE CONDITIONS Part B was stored and subsequently mixed with Part A as described in Example I. The resultant solution was diluted in the same manner as in Example I. The developing characteristics of the aged solution are set forth in Table 2.

TEST PROCEDURE Evaluation of storage stability of aqueous acetic acid solutions of 1-phenyl-3-pyrazolid0ne-Examples I-I V Sensitometrically exposed film strips containing fifteen different index areas were developed in each of the developing baths in Examples I-IV containing the aged 1- phenyl-3-pyrazolidone reducing solution of Part B. The developing efiiciency of each of these developing baths was measured and compared with that of a control comprising the same developing bath with the exception that fresh or unaged 1-phenyl-3-pyrazolidone solution was employed. Developing efiiciency Was measured by determining the base fog and optical density of each of the fifteen different index areas of the control strips. The results are given in Tables 1 and 2.

In addition to the compositions of the examples, 1- phenyl-3-pyrazolidone Was stored admixed with Part A (pH approximately 11.6) at 50 C. for two weeks, which is equivalent to about seven months at C. At the end of two weeks, it was diluted as in Example I, and its developing efiiciency measured and compared with the final use developing bath which contained fresh developer concentrate and fresh 1-phenyl-3-pyrazolidone. Part A without 1-phenyl-3-pyrazolidone was also stored at 50 C. for two weeks. At the end of two weeks, fresh 1-phenyl-3- pyrazolidone was added to Part A and the resultant solution was diluted as in Example I, and its developing efiiciency measured. The results are given in Table 3. The numbers appearing there are optical density measurements as determined by an Ansco-Sweet densitometer.

For convenience, the compositions were evaluated in groups as indicated by the tables. Comparisons of optical densities are properly made between the examples of each table and not between the densities of the different tables. This is so because the tests were conducted at different times, using film having diiferent sensitivities.

TABLE 1.-FINAL USE DEVELOPING BATH [4 Week Storage at 50 0.]

Index Area Control 1 Example I Example II 0. 24 0. 23 0. 24 0. 32 0. 0. 30 O. 0. 36 O. 36 0.49 0.45 0. 0. 62 0. 57 0. 56 0. 76 0. 70 O. 71 0. 99 0. 88 0. 88 1. 14 l. 08 1. 08 1. 46 1. 35 1. 34 1. 64 1. 61 1. 61 1. 89 1. 84 1. 86 2. l6 2. 14 2. 14 2. 44 2. 46 2. 42 2. 73 2. 76 2. 74 3. O2 3. 11 3. 06 0 12 0.12 0. 13

1 Fresh unaged solutions of parts A and B, Example I.

TABLE 2.-FINAL USE DEVELOPING BATH [4 Week Storage at 0.]

Index Area Control 1 Example 111 Example IV 1 Fresh unaged solutions of parts A and B, Example 1.

Tables 1 and 2 demonstrate that the optical densities of final use developing baths to which aged 1-phenyl-3- pyrazolidone solutions had been added are virtually idenveloper concentrate containing 1-phenyl-3-pyrazolidone, are markedly lower than those of a control or a final use developing bath D, comprising an aged developer concentrate and fresh 1-phenyl-3-pyrazolidone. These results underscore the deterioration upon storage of an alkaline solution of 1-phenyl-3-pyrazolidone.

TABLE 3.FINAL USE DEVELOPING BATH Index Area Control l Bath 0 2 Bath D 8 1 Fresh developer concentrate (Part A) and fresh 1-phenyl-3-pyrazolidone used to make up final use developing bath.

2 Made by diluting an aged developer concentrate comprising Part A and l-phenyl-3-pyrazolidone after storage of said developer concentrate at 50 C. for 2 weeksdilution like Example I.

5 Made by adding fresh 1-phenyl-3-pyrazolidone to developer concentrate (Part A) after storage of Part A for 2 weeks at 50 C., then diluting the resultant solution like Example I.

The foregoing results illustrate the stability toward deterioration upon aging of the aqueous acetic acid l-phenyl-3-pyrazolidone solutions of the present invention, and the total independence of such solutions from the requirement of anhydrous solvents to yield developing baths having full speed, capacity and contrast.

It should be understood that in the foregoing experiments all of the test strips were fixed in conventional hypo fixing baths.

While several particular embodiments of this invention are suggested above, it will be understood of course that the invention is not to be limited thereto since many modi fications may be made and it is contemplated, therefore, by the appended claims to cover any such modifications as fall within the true spirit and scope of this invention.

We claim:

1. A process for developing photographic silver halide emulsions which comprises providing a stabilized developing system comprising:

(a) providing a component package comprising a solution of a l-phenyl-3-pyrazolidone developing agent, said solution consisting essentially of an aqueous acetic acid solution containing from about 15 to by volume of acetic acid and at least about 2 grams of a 1-phenyl-3-pyrazolidone developing agent per ml. of said aqueous acetic solution, said solution being characterized in being stable during storage for more than one year at ambient temperatures,

(b) providing another component package solution comprising a developer composition containing alkaline components and developer components free from a 1-phenyl-3-pyrazolidone developing agent,

(c) Storing said component package solutions in separate unmixed condition,

(d) admixing said developing agent component solution to form a developing solution for silver halide emulsion at the time of use,

(e) and developing a silver halide emulsion in said admixture.

2. The process for developing photographic silver halide emulsions according to claim 1 wherein the component solution provided in step (a) is a stabilized aqueous solution consisting essentially of water, acetic acid, and a 1-phenyl-3-pyrazolidone developing agent, the proportions of said water, acetic acid and a l-phenyl-3- pyrazolidone being defined by the area bounded by lines interconnecting the points A, B, C and D on the accompanying drawing.

3. The process according to claim 2 wherein the area 7 is defined by the lines interconnecting the points E, B, C and D in the accompanying drawing.

4. The process according to claim 1 wherein the component solution provided in step (a) is a stabilized solution consisting essentially of about 95 parts by volume of acetic acid, about 5 parts by volume of water and a 1-phenyl-3-pyrazolidone developing agent in the proportion of about 20 grams per 100 ml. of the aqueous acetic acid solution.

5. A process according to claim 1 wherein the component solution provided in step (a) is a stabilized solution consisting essentially of about 90 parts by volume acetic acid, about parts by volume water, and a 1- phenyl-3-pyrazolidone developing agent in the proportion of about 20 grams per 100 ml. of the said aqueous acetic acid solution.

6. A process according to claim 1 wherein the component solution provided in step (a) is a stabilized solution consisting essentially of about 80 parts by volume acetic acid, about 20 parts by volume water, and a 1- pheny1-3-pyrazolidone developing agent in the proportion 8 of about grams per 100 ml. of the aqueous acetic acid solution.

7. A process according to claim 1 wherein the component solution provided in step (a) is a stabilized solution consisting essentially of about parts by volume acetic acid, about 30 parts by volume water, and a 1- phenyl-3pyrazolidone developing agent in the proportion of about 20 grams per ml. of the aqueous acetic acid solution.

References Cited FOREIGN PATENTS 900,171 7/1962 Great Britain.

OTHER REFERENCES Alletag, G. C., Degradation of Phenidone in Developer Solutions During Storage, Phot. Sci. & Eng, vol. 2, N0. 4, December 1958, pp. 2l3218.

NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner. 

